Reasons of Poor Eyesight
The first reason for poor eyesight is reading for long hours. This looks strange. But it has a reason.
Let us look at the working of eye to understand the reasons of poor eyesight.
Cornea is the top layer of eye. It is white. It has 65 to 75% of total focusing power (optical power) of the eye. But with fixed focus we can see thing clear only within a very short distance. But in our day to day life we need to look at near as well as distant objects every other minute.
To take care of this, the eye has one more lens behind iris and cornea. This is flexible lens which changes shape easily. This lens is held by light sensitive cells. There is a range of light that can be handled by these light sensitive cells.
When we look at the distant object, the amount of light that can be reflected back to the eye is very less as compared to the amount of light that is reflected back from near object.
Iris controls the amount of light that enters in the eye. For distant objects when light reflected is less the iris dilates and allows more light to enter the eye. Iris stays open for more time to allow more light to enter the eye.
Based on the amount of light that enters the eye through iris, the shape of the lens behind iris is changed.
During long hours of reading, the eyes remain focused on near object for long hours. The light sensitive cells do not move the internal lens. When we spend long hours in reading the light sensitive cells start losing some of the light sensitivity. The lose the capability of reshaping the lens shape based on the distance of the object.
Solution
- We should have variable lighting in the reading room. There should be more than 4-5 light sources which should keep switching on and off. At some times only one source of light should be switched on, at others 2 or 3 or 4. That will change the amount of light that enters the eye. That will keep the light sensitive cells in perfect shape and we will never have to wear the specs.
- Another option is to close eyes after every few minutes and look at a distant object for 10 to 15 second. Again close your eye and start reading.
What is not useful
Each eye is held by 6 muscles that control eye movement. And one muscle which control the movement of eyelid. The poor vision is never caused due to weakness of these muscles. So exercising these muscles will not be of any help.
Rather those eye muscles can cause damage to the eye. Excessive exercises cause swelling. Swelling means more fluids in the surrounding muscles. More fluids in surrounding muscles means less light sensivity.